Mushrooms belong to the kingdom of Fungi, a group very distinct from plants, animals and bacteria. Fungi lack the most important feature of plants: the ability to use energy from the sun directly through Chlorophyll. Thus, fungi depend on other organisms for food, absorbing nutrients from the organic material in which they live. The living body of the fungus is mycelium made out of a tiny web of threads (or filaments) called hyphae. Under specific conditions, sexually compatible hyphae will fuse and start to form spores. The larger spore producing structures (bigger than about 1 mm) are called mushrooms. In nature this is the most striking part of the organism, but in fact it is just the fruiting body and the major part of the living organism is found under the ground or inside the wood.

Mushrooms are not plants, and require different conditions for optimal growth. Plants develop through photosynthesis, a process that converts atmospheric carbon dioxide into carbohydrates, especially cellulose. While sunlight provides an energy source for plants, mushrooms derive all of their energy and growth materials from their growth medium, through biochemical decomposition processes. This does not mean that light is an unnecessary requirement, since some fungi use light as a signal for fruiting. However, all the materials for growth must already be present in the growth medium. 

Mushrooms grow well at relative humidity levels of around 95-100%, and substrate moisture levels of 50 to 75%.Instead of seeds, mushrooms reproduce sexually during underground growth, and asexually through spores. The biotechnological advances that will help ensure mushroom cultivation without pollution and provide mushroom products with health enhancers and get more reliable yields, then improve substrate utilization and control disease more effectively. Either of these can be contaminated with airborne microorganisms, which will interfere with mushroom growth and prevent a healthy crop.

Preparation of mushroom beds

Preparation of bags : Use 60x30 cm polythene bags (both side open).Tie one end of bag, put two holes of 1 cm diameter in the middle.Put handful of cooked straw in the bag to a height of 5 cm; sprinkle about 25 g of spawn. Layer the straw to 25 cm height. Repeat the process to get four layers of spawn and 5 layers of straw. Tie the mouth and arrange beds in tiers in the spawn running room. After 15-20 days, cut and remove the polythene bag and transfer the beds to cropping room. Keep the beds moist by periodical spraying with water.

In the bed system mushrooms are grown in wooden receptacles which are approximately 65" wide×60 foot long. These receptacles may be wider or narrower than 65" and/or they can be shorter or longer than 60 feet long. The depth of these receptacles is generally from 6" to 8" deep, however, they can be any suitable size. In what is referred to as a mushroom house these receptacles are usually stacked in four tiers, In each of these tiers six receptacles are usually stacked in a superimposed arrangement so that one mushroom house contains 4 tiers and 24 receptacles.

In the tray system mushrooms are also grown in wooden receptacles. These receptacles or trays can be square or rectangular, however, the most popular size is 48" wide×72" long×8" deep. In a farm using the tray system approximately 220 of these trays are put into one growing room. The trays are generally stacked four to five trays high and are arranged in eleven rows four stacks to a row. A typical mushroom tray is about 175 cm. long by 120 cm. wide with the tray height being 17.5 cm. and the corner post extending upwardly from the tray sides a further distance of about 12.5-15 cm.

Mushrooms are grown on decaying organic material. This material can be horse manure, hay, cereal straw or a variety of other vegetable wastes. The breakdown of this organic material is accelerated by the mushroom grower by composting. The purpose of composting is to convert the crude, often variable, raw material into a medium rich in nutrition which is specific for the growth of mushrooms. Three different substrates were tried for mushroom production viz., paddy straw, non retted coir pith [obtained by manually extracting the mesocrap] and retted coir pith. Mushroom beds were prepared following the method described by Baskaran et al., (1978) in the case of paddy straw or non retted coir pith as the substrate and the method described by Theradinani and Marimuthu (1991) was adopted for the preparation of beds using retted coir pith as the substrate.

In the case of paddy straw and non retted coir pith, substrates were kept in water overnight, boiled for half an hour, drained and dried. In perforated polythene bags of size 60×30cm, 3 layers of substrate [each of 5 to 8cm thickness] was placed with spawning of each layer. 100gm spawn per mushroom beds was used. The bags were then tied and incubated in the dark for 15 days, after which they were opened and transferred to cropping room were adequate ventilation and moisture was maintained.

In the case of retted coir pith, well perforated polythene bags of size 30cm was first filled with 0.5kg of the substrate and inoculated with pleurotus spawn [at the rate of 100g per kg of the substrate] uniformly over surface and covered with another layer of 0.5kg of coir pith. This process was repeated till the bag was filled. The bag was tied and incubated in a room where adequate moisture and ventilation were present.

The nature and rate of growth and yield characteristics in all the substrates were recorded. Samples were drawn at 10, 20 and 30 days interval to study laccase production and also to estimate the laccase content.